1. Field of Invention
This invention relates in general to well component positioning, and in particular to a device that provides an operator with the location-and-rotation of a tool during wellhead operation.
2. Description of Related Art
The operation of equipment in remote and inaccessible locations, such as subsea wellheads, is difficult because there is no information available as to the condition or the occurrence of an event in such remote location. It is thus difficult to determine if a particular subsea wellhead operation has been successful. Wellhead operations may include landing a casing hanger on the housing seat, properly locating an annulus seal, properly positioning a tool or component at a particular level, or rotating a tool or component to a particular orientation within the wellhead.
The operation and placement of well components in a wellhead housing bore, riser bore, or blowout preventer (BOP) stack is critical in oil and gas drilling operations, especially in offshore operations where down time is very expensive. Thus a variety of approaches have been used in an attempt to provide reliable location-and-rotation of well components. Hard landing a casing hanger can be used as an indicator of location but it can be a false indicator if the hanger gets snagged on debris or other obstruction in the well bore.
An index line has also been used in conjunction with hard landing. However, the index line becomes inaccurate as longer lines are used in deeper waters, which can lead to costly errors in location when setting a tool. Another approach calls for the use of radioactive material to provide a location signal. Overpull can also be used as a location indicator but is not viable for all types of tools.
Acoustic or ferrous metal detectors, as well as magnetic detection units have also been used as location tools. U.S. Pat. No. 4,314,365 shows a system for transmitting and detecting acoustic signals along a drill pipe string, and U.S. Pat. No. 4,862,426 discloses an apparatus that uses acoustic or ferrous metal detectors to determine if certain operations such as landing a casing hanger are completed. German Utility Model Application No. 110 08 413.5 shows a system for detecting tool joints using magnetic detection units in a planar arrangement.
Moreover, a method and apparatus for sensing the profile and position of a well component in a well bore is disclosed in U.S. Pat. No. 6,478,087. The apparatus uses acoustic, ultrasonic, or optical sensors to sense well components and then transmits the information to a display at the surface.
Improvements that make the identification of the location and the rotation of well bore tools and components more reliable, less complicated, less costly, and more accessible are desired. The techniques described below address one or more of the problems described above.